The Mexican Electoral Commission has apologised for an "outrageous" dress worn by an assistant at the first televised debate in the Mexican presidential campaign calendar.

On screen for no more than 30 seconds, model Julia Orayen managed to steal the show in a tight, white dress with a plunging neckline while handing out debate cards.

"We are sorry about the production error associated with the clothing of one of the assistants during the first presidential debate and want to apologise to the citizens and the candidates for the presidency," the Commission said in a statement released today.

The dress was branded an "outrageous stereotype" that overshadowed what should have been a serious event, by Lorenzo Cordova, a member of the Commission.